Material handling containers are frequently provided with covers to enclose the contents of the container or to secure the contents against pilferage. When used merely to enclose the container, the cover commonly is provided with a peripheral flange which extends downwardly around the edge of the container. In many cases the cover is provided with dimples or recesses which are adapted to engage the rim of the container to prevent the cover from being displaced or dislodged from the container.
Security covers are used primarily during transporting or distributing materials out of the plant and are designed to prevent easy access to the contents and thus curtail pilferage. Should forced entry have occurred, it is readily evidenced by a damaged cover or container, or a broken locking device. Such tampering would be readily apparent when the transported goods are routinely checked at the various transfer points.
U.S. Pat. No. 3,379,341 discloses a security cover in which the cover is provided with a central depressed area and one end of the cover has a hook element which terminates in a horizontal edge that is received between horizontal ledges formed on the outer surface of one of the walls of the container, while the opposite end of the cover and the underlying portion of the rim of the container are formed with aligned holes to receive a locking device.
U.S. Pat. No. 3,360,162 also discloses a type of security cover in which an end of the cover is provided with an outwardly extending tongue that is inserted within a slot in the end wall of the container. The cover can be locked to the cover of the container by inserting a locking device through aligned holes in the opposite end of the cover and the rim of the container.